Stellar physics focuses on how stars form, evolve, and eventually end their lives. In this topic you study how interstellar gas clouds collapse under gravity to create protostars, and how nuclear fusion in the core provides the energy that supports a star during most of its lifetime. You examine how temperature, pressure, and composition determine a star’s position on the Hertzsprung–Russell diagram, which is used to track different stages of stellar evolution. The topic also covers how stars of different masses follow different evolutionary paths, leading to outcomes such as white dwarfs, neutron stars, or black holes. By analysing luminosity, surface temperature, spectra, and nuclear processes, stellar physics provides a framework for understanding the life cycles of stars and the mechanisms that shape the structure and history of the universe.

Cosmology deals with the large-scale structure and evolution of the universe. In this topic you study evidence for the expanding universe, including redshift measurements and Hubble’s law, which relates the recession speeds of galaxies to their distance. You examine the Big Bang model, the early development of the universe, and key observations such as the cosmic microwave background that support this framework. Cosmology also introduces ideas about the universe’s composition, including dark matter and dark energy, and how they influence its past and future behaviour. By combining astronomical observations with physical principles, cosmology aims to explain how the universe began, how it has changed, and what its long-term evolution might be.